Readily releasable drive connection for appliance



szmzwmmwygss June 8, 1965 A. RJSPOHR 3,187,360

READILY RELEASABLE DRIVE CONNECTION FOR APPLIANCE Filed Oct. 4, 1963 2 Sheets-Sheet 1 FIGI FIGZFIGB F| 3.4 I B INVENTOR. 36 ALBERT R. SPOHR ATTORNFY United States Patent 3,1875% READHJY RELEASABLE DREVE CUNNECTHQN FGR APPLIANQE Albert R. Spohr, Park Ridge, lilh, assignor to dunbearn (Iorporation, Chicago, ilL, a corporation of illinois Filed (Oct. 4, 1963, Ser. No. 313,898

11 tilaims. Cl. l-22) This invention relates to a readily releasable mechanical drive connection for an appliance, and more specifically to such a connection for a battery operated appliance such as an electric toothbrush.

It is common practice to provide a prime mover which electively drives different devices thus requiring a readily releasable mechanical drive. Although the present invention is of general application, it is specifically illustrated in connection with an electrically driven toothbrush. Electric toothbrushes for use in the home customarily include a compact hand held power unit which preferably comprises an electric drive motor. This electric motor may be energized fromv any source of power including a rechargeable battery. The details of such a battery powered toothbrush are disclosed in a copending application of Albert R. Spohr, Serial No. 353,327, filed March 20, 1964, and assigned to the same assignee as the instant application. 1

Since the power unit of such electric toothbrushes is intended to be used by all members of a family, a plurality of toothbrush attachments are necessarily provided, one for each person in the family, which are adapted to be driven from the common power unit. When an individual member of the family desires to use the power actuated toothbrush, he mounts his individual toothbrush attachment onto the hand held motor unit in driving relation ship therewith. The mechanical drive connection interconnecting the individual toothbrushes and the power unit must be rigid enough accurately to transfer the motion inrparted by the power unit to the brush, and at the same time be easily attached and detached from the power unit by the user of the brush. Moreover, such drive connection should be such as not to become detached except at the will of the user.

Accordingly, it is an object of the present invention to provide an improved readily releasable drive connection for interconnecting a power unit and an appliance driven thereby, which drive connection is rigid and strong enough to transfer the motion imparted by the power unit to the appliance without any looseness or vibration in the drive connection,

It is another object of the present invention to provide a mechanical drive connection between a motor unit and a toothbrush or other attachment whereby the user may easily connect or disconnect the same.

Still another object of the present invention resides in a new and improved toothbrush adapted to be power operated.

it is a further object of the present invention to provide a mechanical drive connection between a driving mechanism and a driven device capable of being readily connected and disconnected by a user which includes means for latching said mechanism and device in driving position so that the user knows when the drive connection is fully established and so that the driven device cannot become detached from the driving mechanism during use thereof.

A still further object of the present invention resides in the provision of a mechanical drive connection for an electric toothbrush or other driven device, said connection having a drive portion to transfer the driving impulse to the toothbrush or other driven device and also having a holding portion to firmly hold the toothbrush or other assists Federated June 8, 1965 ice driven device in driving engagement and prevent any looseness or vibration.

Further objects and advantages of the present invention will become apparent as the following description proceeds, and the features of novelty which characterize the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

These and further objects of the present invention will become apparent from the following description taken with the accompanying drawings in which:

FIG. 1 is a perspective View of a power or driving unit with which the driven device shown in dotted lines is associated embodying the drive connection of the present invention, said device being illustrated as a toothbrush;

FIG. 2 is a front view of a toothbrush embodying the present invention; 1

FIG. 3 is a side view of the toothbrush of FIG. 2 shown in driving relationship with the drive shaft of the power unit, the power unit other than the drive shaft being shown in broken lines;

FIG. 4 is an enlarged fragmentary view of the drive connection bet-ween the power unit and the toothbrush of FIG. 1, the latter being shown in dotted lines and the portion of the power unit other than the drive connection also being shown in dotted lines;

FIG. 5 is a fragmentary view of the drive shaft of FIG. 4 looking in the direction of the arrows 5-5 in FIG. 4;

FIG. 6 is a top view of the drive shaft of FIG. 5;

FIG. 7 is a greatly enlarged fragmentary sectional view taken on line ?7 of PEG. 2; 7

FIG. 8 is an end view of FIG. 7, assuming that P16. 7 shows the complete construction;

FIG. 9 is a sectional view taken on line -9 of FIG. 8; and

FIG. 10 is a perspective view of the recess defined in the shank of the toothbrush of the present invention,

Briefly, the mechanical drive connection of the present invention includes a driving member or drive shaft projecting from a power unit and an appliance specifically illustrated as a toothbrush having a hollow shank portion adapted to receive the drive shaft therein. The drive shaft has an intermediate cylindrical portion and an end drive portion having opposed fiat surfaces. It also includes an annular latching recess at the end of the cylin drical portion remote from the drive portion. The recess in the end of the hollow shank of the toothbrush includes an innermost narrow portion defined by opposed flat wall surfaces adapted to snugly receive the opposed fiat surfaces at the end of the drive shaft. These cooperating flat surfaces on the drive shaft and within the recess in the toothbrush shank provide the principal means for transmitting motion from the drive shaft to the brush. The remainder of the recess extending from the fiat wall surfaces to the mouth of the recess at the end of the shank is generally cylindrical and is defined by a relatively thin cylindrical wall portion having a plurality of inwardly projecting longitudinally extending spaced ribs which firmly abut against the cylindrical portion of the drive shaft. This portion of the connection serves the purpose of firmly holding the brush on the drive shaft and thus preventing any loosencss which could result in wobble or vibration. The ends of the ribs adjacent the end of the shank are provided with latching protuberances for engaging the annular latching recess on the drive shaft when the brush is fully connected to the latter, thus preventing the brush from becoming detached from the drive shaft during use thereof. To provide additional resilience to cause engagement of the latching means, the thin cylindrical wall portion is provided with a slit portion. In accordance with the invention, the mechanical drive connection is adapted to be easily connected and disconnected by the user.

Referring now to the drawings, there is illustrated a power unit adapted to drive a toothbrush or other appliance generally designated as 21. In the illustrated embodiment this power unit 20 is adapted to be held in the hand during use and is preferably provided with an electric motor energized from rechargeable batteries forming part of the unit 20. The details of motor 20 are disclosed in the above-mentioned copending application and, aside from the construction of the drive shaft, form no part of the present invention. Projecting from one end of the power unit 20 is a shaft 22 which may be rotated, oscillated or otherwise driven by the power unit 20. In a device built in accordance with the present invention, drive shaft 22 was oscillated at high speed which caused similar oscillation of appliance 21.

In accordance with the present invention, drive shaft 22, insofar as the portion thereof projecting from power unit 20 is concerned, comprises a cylindrical portion 22a and an end drive portion 2212. An annular latching recess 24 is defined in the cylindrical portion 22a remote from the drive portion 22b. Drive portion 22b includes oppositely disposed fiat surfaces 26 which at the lower ends thereof, as viewed in FIGS. 4 and 6 of the drawings, gradually merge into the cylindrical portion 22a. The annular latching recess 24 is defined by a pair of angular annular surfaces 240 and 24b.

The appliance 21 to be driven by power unit 20 is illustrated as a toothbrush preferably comprising a molded plastic portion 28 similar to the conventional toothbrush supporting brush bristles 30 at one end thereof.

In order to secure and drive appliance 21 from drive shaft 22, the molded portion 28 remote from bristles 30, which might be termed the brush shank, includes a hollow bore or recess 32 having its mouth at the end of the shank and extending in a longitudinal direction into the shank so as to receive the drive shaft 22 therein. As best shown in FIG. 10 of the drawings, the recess 32 includes three sections 32a, 32b, and 32c. The innermost section 32a is provided for molding purposes only and is not an operative part of the drive connection of the present invention. The recess section 32b is defined by a pair of opposed flat wall surfaces 36 spaced to receive snugly therebetween the oppositely disposed flat surfaces 26 of drive shaft 22. The portions of recess 32 defined by fiat wall surfaces 36 are designated as 36. Moreover, this recess portion 32b is of a width to accommodate the section 22b of shank 22. The recess section 320 of recess 32 is a cylindrical section defined by a thin cylindrical wall portion 28a which is thin enough to be somewhat resilient for a purpose described hereinafter. In fact, to increase the resilience of the walls defining recess section 32c, a longitudinally extending slit 38 is defined in the walls defining recess section 320. The slit is shown as a projec tion 38 of cavity 32 in FIG. 10 of the drawings.

To provide a drive connection with drive shaft 22 which will be rigid and which will not result in wobble or vibration, there are provided, in accordance with the present invention, a plurality of spaced longitudinally extending ribs 40, 41 and 42 disposed within recess section 32c and integrally formed with the shank portion of brush 21. These ribs terminate a short distance before the lower end of recess section 32c, as viewed in FIGS. 7 and 8 of the drawings. Moreover, the projecting surfaces of these ribs in the longitudinal direction thereof define a cylindrical surface for snugly engaging the cylindrical portion 22a of drive shaft 22. The location of these ribs relative to recess 32 is designated in FIG. 10 of the drawings by the reference numerals 40', 41' and 42' corresponding to ribs 40, 41 and 42, respectively.

In order to latch the appliance 21 to drive shaft 22, one or more of the ribs 40, 41 and 4-2 are provided adjacent the ends thereof with latching protuberances designated as 49a, 41a and 42a, respectively. The position of the protuberance 42a relative to recess 32 is designated as 42a in FIG. 10 of the drawings. These protuberances are receivable in the latching recess 24 of drive shaft 22. The slit 38 and the resilience of the walls defining recess section 32c permit the necessary distortion so the protuberances 40a, 41a and 42a can slide over cylindrical surface 22a of drive shaft 22 and then engage latching recess 24-.

In a device constructed in accordance with the present invention, drive shaft 22 was fabricated of metal, while the portion 28 of appliance 21 was formed of molded plastic having a slight degree of flexibility. When the drive shaft 22 is received within recess 32, the opposed flat surfaces 26 on the drive shaft abut against the opposed fiat wall surfaces 36 defining recess section 321) in the shank of molded plastic portion 28. By means of these interengaging opposed flat surfaces, the oscillatory motion of the drive shaft 22 is imparted to the toothbrush or other appliance 21. It should be noted that the walls defining recess section 32b are relatively thick and, therefore, provide a strong driving connection which will not crack or break.

It can be seen that the appliance 21 can be mounted on drive shaft 22 in either one of two positions which are opposed to each other. In each of these positions the flat surfaces 26 and 36 will be in mutually abutting relation. In addition, drive portion 2211 can only be received in recess portion 32b in these two positions, because of the keyed characteristic of the shaft and the recess. Therefore, when the appliance 21 is mounted on the drive shaft 22 in one of the two possible positions, the appliance 21 will not be capable of any rotary motion except for that imparted by the shaft itself.

From the above description it will be apparent that the ribs 40, 41 and 42 abut tightly against the generally cylindrical portion 22a of the drive shaft 22. This relationship holds the toothbrush 21 firmly on the drive shaft and prevents any looseness or wobble in the brush as it is being driven by the drive shaft. Furthermore, when the drive shaft 22 is fully received within recess 32 of appliance 21, the protuberances Eda, 41a and 42a on the inwardly extending ribs 49, 41 and 42, respectively, will be received in annular latching recess or groove 24- in the drive shaft 22. Thus, these protuberances cooperate with the groove in releasably locking the toothbrush attachment firmly onto the drive shaft 22. It will be understood that as the toothbrush 21 is being slid onto the drive shaft 22 the walls of the molded portion 28 thereof deform slightly to allow the protuberances to slide over the shank portion 22a of the drive shaft until they reach the groove 24. This deforming characteristic is possible due to the slightly resilient molded plastic construction of the toothbrush shank and also because of the longitudinally extending slit 38.

Although in the illustrated embodiment the appliance comprise a toothbrush, it should be understood that the drive connection of the present invention could be used for other appliances without departing from the scope of the invention.

While there has been shown and described a particular embodiment of the present invention, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the invention in its broader aspects, and it is, therefore, contemplated in the appended claim to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. A toothbrush comprising a molded brush supporting portion, bristles supported near one end of said portion, means at the other end of said portion for making driving connection with a prime mover, said last mentioned means comprising a multisection longitudinally extending recess in said other end, one section of said recess being defined by opposed flat surfaces for making driving connection with a suitable driving means, another section of said recess being defined by a thin cylindrical wall portion and including a plurality of spaced longitudinally extending inwardly directed ribs adapted for snugly engaging a cylindrical surface, and inwardly directed latching protuberances on one of said ribs adjacent the ends thereof. 7

2. The toothbrush of claim 1 wherein said cylindrical wall portion is provided with a slit to increase the resilience thereof.

3. A driving connection for releasably connecting a driving shaft to a driven shaft wherein said driving shaft includes a cylindrical portion and an end driving portion, said end driving porton havng at least one fiat side, a latching recess in the portion of said driving shaft remote from said end driving portion, said driven shaft including recess means in one end thereof, said recess means having an inner portion with at least one flat wall surface adapted to drivingly engage said flat side, projecting holding means at the outward end of said recess means for snugly receiving the cylindrical portion of said driving shaft, and protuberance means within said recess means cooperating with said latching recess to releasably lock said driven shaft onto said driving shaft.

4. The driving connection of claim 3 wherein said driven shaft is of molded plastic and said recess means is defined by a deformable wall.

5.'The driving connection of claim 4 wherein a longitudinally extending slit is provided in said deformable wall extending inwardly from the end of said driven shaft.

6. The driving connection of claim 3 wherein said projecting holding means comprises a plurality of spaced, longitudinally extending, inwardly directed ribs abutting said cylindrical portion of said drive shaft.

7. The driving connection of claim 6 wherein said' latching recess comprises an annular groove in the cylindrical portion of said drive shaft and said protuberance means comprise protuberances on said ribs receivable in said latching recess.

8. A mechanical drive connection for drivingly interconnecting a driving shaft and a toothbrush, said driving shaft comprising a central cylindrical shank portion and an end drive portion, said end drive portion having op-.

positely disposed parallel fiat surfaces, an annular recess in said shank portion spaced from said end drive portion, a driven shaft integral with said toothbrush having an elongated hollow bore in the end thereof, said bore being defined by a deformable wall of said driven shaft, the inner portion of saidlhollow bore being defined by spaced parallel flat wall portions adapted to drivingly receive said end drive portion, a plurality of longitudinally extending inwardly projecting ribs within said bore for snugly engaging said cylindrical portion, means defining a longitudinally extending slit in the wall of said driven shaft between said ribs, and protuberances on said ribs receivable in said annular recess for releasably latching said toothbrush to said driving shaft.

9. A toothbrush comprising a molded brush supporting portion, bristles supported near one end of said por- 6 tion and means at the other end of said portion for making a driving connection with a drive shaft of the type having a cylindrical portion, a flat wall portion and recess means defined in said cylindrical portion of the drive shaft, said driving connection means comprising a multisection recess in said other end, the inner section of said recess being defined by at least one fiat wall adapted to drivingly abut said one flat wall portion on said drive shaft, the outermost portion of said recess including inwardly extending protuberance means adapted to latch in the recess means in said drive shaft, an intermediate section of said recess being defined at least in part by means adapted to drivingly abut a cylindrical portion of said drive shaft, and said driving connection means additionally comprising a longitudinally extending slit in the wall defining said recess. e

10. A driven shaft integral with a toothbrush or other attachment and adapted to be driven in an oscillatory manner comprising a generally cylindrical drive shaft receiving portion having a circular cross-sectional periphery throughout, said drive shaft receiving portion having an end wall containing the mouth of a multisection inwardly extending recess in said driven shaft, an inner section of said recess being defined by opposed fiat surfaces adapted to abuttingly receive in driving relation cooperating opposed flat surfaces on a drive shaft, an outermost portion of said recess being defined by a cylindrical wall portion and including a plurality of longitudinally extending inwardly directed ribs adapted for abuttingly engaging a cylindrical portion of a drive shaft, and an inwardly directed latching protuberance on at least one of said ribs adapted to latch in a cooperating recess in a drive shaft.

111. A toothbrush adapted to be driven by a motor driven drive shaft comprising a molded brush supporting portion, bristles supported near one end of said portion and means at the other end of said portion for making a driving connection with a drive shaft, said driving connection means including a multisection recess in said other end, an inner section of said recess being defined at least in part by an integral portion adapted to make a driving connection with the drive shaft, an outer section of said recess including inwardly extending protuberance means adapted to engage in latching relation with the drive shaft for releasably retaining said toothbrush on the drive shaft, and an intermediate section of said recess being defined at least in part by means adapted to engage a portion of the drive shaft in a manner effective to prevent lateral movement of said toothbrush relative to the drive shaft.

References Cited by the Examiner UNITED STATES PATENTS 2,171,361 8/39 Gits et al. Q. 287-53 X 2,439,262 4/48 Nalbach et a1 15-22 X 2,448,614 9/48 M-iris.

2,965,382 12/60 Schlage 279-77 CHARLES A. WILLMUTH, Primary Examiner. 

1. A TOOTHBRUSH COMPRISING A MOLDED BRUSH SUPPORTING PORTION, BRISTLES SUPPORTED NEAR ONE END OF SAID PORTION, MEANS AT THE OTHER END OF SAID PORTION FOR MAKING DRIVING CONNECTION WITH A PRIME MOVER, SAID LAST MENTIONED MEANS COMPRISING A MULTISECTION LONGITUDINALLY EXTENDING RECESS IN SAID OTHER END, ONE SECTION OF SAID RECESS BEING DEFINED BY OPPOSED FLAT SURFACES FOR MAKING DRIVING CONNECTION WITH A SUITABLE DRIVING MEANS, ANOTHER SECTION OF SAID RECESS BEING DEFINED BY A THIN CYLINDRICAL WALL PORTION AND INCLUDING A PLURALITY OF SPACED LONGITUDINALLY EXTENDING INWARDLY DIRECTED RIBS ADAPTED FOR SNUGLY ENGAGING A CYLINDRICAL SURFACE, AND INWARDLY DIRECTED LATCHING PROTUBERANCES ON ONE OF SAID RIBS ADJACENT THE ENDS THEREOF. 